Eight people were injured Thursday morning, one with a serious spinal injury, during a rush-hour tumble on a downward escalator at Union Station.

"We had about 20 people fall off the escalator and we ended up transporting eight patients," Toronto EMS media coordinator Larry Roberts told CTV.ca.

"Two with more serious injuries went to St. Mike's trauma centre, two went to St. Joseph's Hospital and four were sent to Toronto Western Hospital."

Toronto police Staff Sgt. Greg Cole told CTV.ca the injuries were caused by a "domino effect" as people on the escalator landed on top of each other when a man fell at the bottom of the staircase.

A female victim taken to St. Michael's Hospital suffered a serious spinal injury from the incident, Roberts said.

Others treated suffered "general injuries from being crushed, sore back bumps and bruises," he added.

Roger Rodrigues, who was caught in the pileup, said everything happened so quickly.

"I had maybe three or four people underneath me and a whole bunch of other people on top of me," the 55-year-old said.

"When I heard, 'Oh my god, oh my god,' the gentleman was already falling down on the bottom and what happened was people just couldn't jump over him."

People yelled out for someone to stop the escalator, but no one could hit the emergency stop button. In the panic, no one realized they had to lift the plastic cover to get at it.

Rodrigues was finally able to push the button and the escalator stopped seconds later.

The incident occurred shortly after 7:30 a.m. and was the result of an "escalator malfunction," Roberts said.

Some reports suggested the escalator sped up for an unknown reason.

GO Transit would not comment on the cause until the investigation was complete.

With a report from CTV's Janice Golding